Descriptions

This thesis reports on an investigation of flow patterns in
shallow geothermal wells in Klamath Falls, Oregon, Although
wells have been extensively used in the area, the exact nature of
the flows in the wells has not been characterized.
Flow characterization is a principal object of this study.
Horizontal crossflows of geothermal fluid may occur at upper and/or
lower levels in the well where perforations in the well casing are
situated. In addition, natural convection may induce vertical flows
within the well casing which would be influenced by the presence or
absence of a heat exchanger.
Preliminary vertical flow measurements were made with a
type of turbinemeter called a "spinner" which was calibrated in a
vertical pipe. This type of instrument had limitations in regard to
the overall objectives of the study in that (i) the spinner partially
blocked flow in the well, possibly altering flow patterns and rates,
and (ii) the spinner could not detect or measure horizontal flows.
In order to obtain a more satisfactory flow-measuring method,
a literature search on flow measurement in confined spaces was
undertaken. As a result of the search, a hot-film anemometer was
selected to make the detailed flow measurements.
The hot-film anemometer was a two-sensor probe that was
calibrated in a special calibration system. The high-temperature
water in the system was pressurized so that local boiling would not
occur at the heated hot-film surface. A number of difficulties
occurred with the probe during calibration, possibly due to the
severe environment.
Measurements of vertical and horizontal flows were attempted
on a single cased well with no downhole heat exchanger. A steel cage
was built to provide protection for the probe when in the well.
Vertical flow measurements showed agreement with past analytical
work and also confirmed the effect of spinner flow blockages.
Turbulence in the lower perforation region was detected with the
vertical flow Measuring channel. Turbulence in the tower
perforation region was again detected with the horizontal flow
measuring channel. There was difficulty in separating horizontal
and vertical flow components. No evidence of high horizontal
velocities was found.